1. Field of the Invention
The present invention relates to an element-selecting method, and more particularly, to an element-selecting method capable of reducing a toggle rate of a Digital to Analog Converter (DAC).
2. Description of the Prior Art
The DAC is utilized for converting a multi-bit digital input signal SIN into an analog output signal SOUT. For example, the DAC has M converting elements EL1˜ELM, wherein M represents a positive integer. When the DAC receives the multi-bit digital input signal SDI, a number of the converting elements of the converting elements EL1˜ELM is selected for respectively outputting a unit signal and the unit signals are combined for forming the analog output signal SOUT.
In the prior art, the element-selecting method, which is a Dynamic Element Matching (DEM) method, is utilized for reducing the noise generated by the mismatch of the converting elements of the DAC by means of balancing selected times of the converting elements of the DAC. However, when the noise-shaping ability of the element-selecting method is improved, the toggle rate, which means the averaged number of elements of DAC changing their states in one conversion step, of the DAC increases. Since the more converting elements toggle, the more glitch and dynamic errors are introduced into the analog output signal SOUT. Hence, the performance of the DAC is degraded, causing a great inconvenience.